Active halogen compounds and processes for their production



Patented June 7, 1949 I ACTIVE HALOGEN COMPOUNDS AND PROC- ESSES FORTHEIR PRODUCTION William C. Arsem, Bethesda, Md.

No Drawing. Application October 30, 1944, Serial No. 561,166

9 Claims. 1

This invention relates to a process for preparing organic N-halogencompounds and to new compounds prepared by this process.

One object of the invention is to produce compounds having highpercentages of active halogen in a state of high purity and with goodyields.

Another object is to produce from organic compounds containing thegroups =NH or --NH: other compounds in which all of the hydrogen atomsattached to nitrogen, which are herein called N-hydrogen atoms, or apredetermined fraction thereof, are replaced by active halogen atoms;and, in general, to produce from organic compounds containing amultiplicity of N-hydrogen atoms the corresponding N-halogen compoundsin which all or a predetermined number of the N-hydrogen atoms have beenreplaced by active N-halogen atoms.

Some specific objects of the invention are the preparation ofN-hexachlor melamine, N-hexaiodo melamine and other fully N-halogenatedderivatives of the amides of cyanuric acid: also N- hexachlortriethylene tetramine and other N- halogenated polyethylene polyamines.

Some examples of N-halogen compounds are:

N-monochlor ethylamine, C2HNHC1 N-dichlor ethylamine, C2H5NC1:N-monobrom acetamide, CH1CONHBr N-iodo succinimlde, CzH4(CO)2NI N-chlorphthalimide, CeHdCOhNCl possible by such procedures to replace by activehalogen all of the N-hydrogen in certain compounds.

The difiiculties encountered in producing completely N-halogenatedorganic compounds are due to their high reactivity. The N-halogen 2compounds react with water according to the following equations:

m-Nx 11,0

In these equationsR may represent any radical attached to =NH or to-NH2, and X is a halogen atom. In the presence of an acid theequilibrium is displaced toward the left and there is very littlehydrolysis. In an alkaline solution the equilibrium is displaced towardthe right and a portion or even all of the active halogen may beremoved.

Some N-halogen compounds in the presence of alkali undergo anon-reversible decomposition. The N-chloramides' and N-chlorimides ofcarboxylic acids are decomposed in alkaline solutions with eliminationof the carbonyl group. For example, N-monochloracetamide yieldsmethylamine CH3.CO.NHCl-l-NaOH CH3.NH2+NaC1+C0r and N-chlorphthalimideyields anthranilic acid C O OH NaCl CO! The N-halogen compounds act asoxidizing agents. For example, an N-chlor compound will react with aniodide in acid solution, one atom of positive chlorine setting free twoatoms of iodine.

4- H O R-NH: HOX

R -NH. HOX

This reaction is made use of in analyzing N-chlor compounds to determinethe percentage of active chlorine. Similarly, an N-chlor compound willoxidize hydrochloric acid or hydrobromic acid forming free chlorine orbromine.

It is evident that an organic N-halogen compound can be successfullyprepared only under conditions permitting its survival, and that thewhile the second stage is the reaction or hypochlorous acid with theN-hydrogen compound R-NH: H001 R-N II the N-hydrogen compound does nothave a basic character, the hydrochloric acid will accumulate in themixture until the destruction of the N-chlor compound by the reactionjust balances its rate of formation, and under these conditions verylittle oi the N-chlor compound will be formed. It the N-hydrogencompound has a basic character, a portion oi it will serve to neutralizesome of the hydrochloric acid, but the portion so utilized will not beavailable for N-chlorination. In either case a low yield will result,and it the N-hydrogen compound contains more than one replaceableN-hydrogen atom in the molecule, only a partially N-halogenated compoundwill be obtained.

If an alkaline substance is added to neutralize the hydrochloric acidanother difllculty arises. In partly N-halogenated compounds or the typethe N-hydrogen is acidic because of the presence of the halogen atom,and the acid character is enhanced if the radical R contains an acidicgroup such as :00 or $02. In compounds containing more than one =NHgroup, the introduction oi N-halogen into one of these groups confers amore acid character upon the N-hydrogen of the other =NH groupsespecially if they are near each other in the molecule. In alkalineliquids therefore, the residual N-hydrogen or a partially N-halogenatedcompound derived from an N-hydrogen compound containing one or more NH:groups or a plurality of NH groups is more readily replaced by a metalthan by a positive halogen, and it is impossible to eflect complete N-halogenation of such compounds in alkaline solutions.

When melamine suspended in water is treated with chlorine, the initialreaction between chlorine and water produces hypochlorous andhydrochloric acids, then some or the melamine reacts with hypochlorousacid to form, partially N-chlorinated derivatives, while another portionof the melamine combines with the tree hydrochloric acid to form a salt.For each molecule of hypochlorous acid which reacts with an N-hydrogenatom to replace it with an N-chlorine atom, one molecule of hydrochloricacid must be neutralized, and for this purpose one basic --NI-I2 groupmust be available. It is impossible under these conditions to introducemore than a small proportion of the theoretically possible six.N-chlorine atoms into a molecule of melamine. Free melamine must bepresent to act as a base for the fixation of hydrochloric acid, and itis not possible to chlorinate completely a portion of the melamine whilesome of it remains free of N- chlorine and retains a basic character.The product resulting from the chlorination of a water suspension ofmelamine is therefore a mixture of the lower chlorinated derivatives.

A similar result is to be expected from attempts to chlorinate in thepresence of water, using elementary chlorine, any N-hydrogen compound ofthe melamine group having more than one replaceable N-hydrogen in themolecule, such as ammeline or ammelide, or, in general, any compoundcontaining a plurality of N-hydrogen atoms, and only partiallyN-chlorinated compounds can be obtained in this manner.

If an alkaline substance, such as sodium or calcium hydroxide, is addedto the reaction mixture when attempting to chlorinate melamine in watersuspension, water-soluble derivatives of partly N- chlorinated melamineare formed. These soluble derivatives probably contain the grouping inwhich M stands for one equivalent of the metal corresponding to thealkaline hydroxide which was added. From such a water-solublederivative, a mineral acid will set free a partly N-chlorinatedmelamine.

The impossibility of efiecting complete N-halogenation of an N-hydro'gencompound in water suspension by treatment with an elementary halogeneither with or without the addition oi an alkaline hydroxide isillustrated by data presented in U. S. patents numbered 2,184,883,2,184,886 and 2,184,888 in which incompletely halogenated melamines areobtained by halogenation oi melamine in water. Specifically, in Patent2,184,883, Example #I describes the chlorination of melamine in aqueoussuspension yielding a product containing 74% active chlorine. Thisamount of active chlorine corresponds to two atoms of N- chlorine in themolecule, whereas if six atoms, the possible maximum number, had beenintroduced, the product would have contained 128% of active chlorine.Example III of Patent 2,184,886 and Example VII of Patent 2,184,888describe the chlorination of a melamine suspension containing calciumhydroxide which yielded a product containing 88.5% active chlorinecorresponding to 2.8 atoms of N-chlorine in the molecule. Example I ofPatent 2,184,888 describes the bromination of melamine in Water whichgave a product containing 112% active bromine, corresponding to only twoatoms of N-bromine in the molecule instead of the maximum possiblenumber, six. Example 11 of the same patent describes the treatment ofmelamine with a solution of iodine in sodium hydroxide which gave aproduct containing less than two atoms of active iodine in the molecule.

The failure in these examples to obtain completely N-halogenatedcompounds containing six atoms of N-halogen in the molecule was due tothe conditions of the reaction, and not to limiting the duration of theprocess.

I have found that N-halogen derivatives of organic nitrogen compoundswhich contain replaceable hydrogen attached to nitrogen may best beprepared by reacting such N-hydrogen compounds with hypohalogen acids inweakly acid solutions. Such weakly acid solutions may be obtained byusing acids with small dissociation constants, or by buffering acids ofgreater strength.

A convenient way of employing this method to produce N-chlor compoundsis to use a solution of sodium hypochlorite to which acetic acid inexcess has been added. Such a solution is an efiective agent for theintroduction of active or positive chlorine in place of N-hydrogen inorganic compounds. Another way of producing a chlorlnating solution ofthis type is to pass gaseous chlorine into a solution of sodium acetate.

Similarly, solutions of sodium hypobromite or sodium hypoioditeacidified with acetic acid in excess may be used for the introduction ofthe corresponding active halogens into N-hydrogen compounds, andequivalent solutions may be obtained by treating solutions of sodiumacetate with elementary bromine or iodine. Instead of acetic acid, otheracids not readily oxidized or halogenated may be used, for examplepropionic acid or chloracetic acid.

In carrying out the process the N-hydrogen compound may be dissolved,suspended or emulsified in water and the halogenating solution added.Alternatively, the N-hydrogen compound may be mixed with acetic acid orother suitable acid and then the solution of hypohalite added, whereuponthe hypohalogen acid is set free and reacts with the N -hydrogencompound to produce the N-halo-compound.

The reaction is practically quantitative andcan be used to replace allor a definite proportion of the replaceable hydrogen in an N-hydrogencompound by active halogen. The proportion of halogen introduced isdetermined by the amount of active halogen supplied as hypohalite inrelation to the amount of N-hydrogen compound to be N- halogenated. Forinstance, melamine, which has six N-hydrogen atoms, can be N-halogenatedby the methods described to yield distinct compounds containing from oneto six N-halogen atoms.

The reaction is of general applicability to N- hydrogen compounds,including primary and secondary amines ofthe aliphatic and aromaticseries, amides and imides of carboxylic or sulphonic acids, amino acids,heterocyclic ring compounds such as melamine, ammeline, ammelide andazines of various types and substitution derivatives thereof containingalkyl, alkoxyl or acyl groups, melam, melem, melamine resins, urea'process is the production of N-hexachlor melamine in which all theN-hydrogen atoms of melamine are replaced by active chlorine. Incarrying out the process, melamine in pulverized form is treated with aweakly acid solution containing hypochlorous acid. This may be done inseveral ways. Melamine may be suspended or dissolved in water containingacetic acid and a solution of hypochlorous acid added. A sodiumhypochlorite solution may be added to a suspension of meh- I mine inwater containing enough acetic acid to liberate all the hypochlorousacid, with an additional amount of acetic to maintain an acid reaction,that is, a pH- less than 7. N-hexabrom melamine and N-hexaiodo melaminecan be produced by analogous procedures. partial N-halogenation ofmelamine can be efiected by employing suitable proportions of thereacting components. N-hexachlor melamine may be used as an agent foreffecting N -chlorination of melamine to produce derivatives containingless than six atoms of N-chlorine. For example, one molecule ofN-hexachlor melamine will react with one molecule of melamine to givetwo molecules of N-trichlor melamine. N-hexachlor melamine may be usedfor the N- chlorination of N-hydrogen compounds other than melamine.

The structural formula of N-hexachlor melamine may be considered to beeither of the following, or an equilibrium mixture of both.

According to the accepted practice in appraising commercial bleachingagents containing hypochlorites the active halogen content or the cas anindex of comparison only when the compounds have the same kind ofhalogen. If an N-chlor compound and an N-iodo compound having the sameactive halogen content are compared, the N-chlor compound is moreeffective, weight for weight, than the N-iodo compound. If two compoundshaving the same number of active halogen atoms in the molecule arecompared, the..N-chlor compound will be more effective, weight forweight, than the iodo compound although the latter will have a higheractive halogen content. The difilculty in comparing active compoundscontaining diiierent halogens is due to the different atomic weights ofthe halogens.

A better basis for comparing different N-halogen compounds is theequivalent weight which is found by dividing the molecular weight of anN-halogen compound by twice the number of N-halogen atoms in themolecule. The lower the equivalent weight of a compound, the less willbe required to produce a given quantitative effect.

The following table gives a list of important organic N-halogencompounds which can be made by the procedures outlined above with theequivalent weight and active halogen content of each. They are arrangedin descending order of efiectiveness per unit weight as oxidizingagents,-

which is also the order of increasing equivalent weight. The activehalogen content of each compound is also stated. Three commercialproducts 1 are included in the table: calcium hypochlorite, chloride oflime and Dichloramine-T Quantitative which is a commercial name forp-toluene suliondichloramide.

Active Molec- Active Equiv-' ular halogen alent 23;? weight atoms weightper e II-Eexachlor meliartrlilinle. 91.. 333 6 27. 75 128 xachlo e one ein f 353 6 29.4 120. 5 N-nonachlor melam 545. 5 9 30. 3 119. 6 N-tetrachlor ammeline. 205 4 33. 1 107 N-chlor methyleneurea. 141 2 35. 2100. 7 N-dlchlor butylamine 142 2 35. 5 100.0 N-trichlor melamine 220. 53 38. 25 93 N-dichlor melamine 195 2 48. 75 72. 8 High-lest hypochlorite70 Dichloramine-T 240 2 00 50. 2 N-dichlor dlethyl-barbituric acid 253 263. 2 56. 2 N-hexniodo melamine 882 0 73. 5 173 N-monochlor melamine160. 5 1 80. 44. 2 N -ch1or phthelimide 181. 5 1 90. 7 39. l Chloride oflime.. N-brom hthalimide 226 l 113 71 N-iodo p thalirnide 273 1 136.791. 5 20 The highly halogenated substances produced by the methodsherein described are particularly well adapted for the following uses:

a. Antiseptics.

b. Disinfectants.

c. Oxidizing agents.

d. Oxidation catalysts.

e. Drying agents for paints, oils, varnishes and 30 synthetic resins.

.f. Bleaching agents for fibres, textile materials, fats and oils.

0. Intermediate compounds for the preparation of other derivatives.

h. Chemical reagents.

To prepare antiseptic ointments or protective salves, these substancesmay be dissolved or dispersed in petrolatum, lanolin, hydrogenated oil,etc. To prepare disinfecting or decontaminating solutions they may bedissolved in organic solvents or aqueous alkaline liquids. They may beused as germicidal components of toilet preparations or medicinalproducts. They may be used in a substantially pure state or in admixturewith other substances as a constituent of a dry mixture, paste,suspension or solution.

Since the completely N-halogenated compounds contain higher percentagesof active halogen than the corresponding partly N-halogenated compounds,they are more effective and more economical to use.

The completely N-halogenated compounds are only very slightly soluble inwater, but are soluble in organic solvents. They are generally quitestable for long periods, while the partly N-halogenated products aremore soluble in water and less stable. Y

The first five products in the above tabulated list, which arecompletely N-chlorinated, are

especially valuable in applications such as those listed, and for whicha compound having a high content of active chlorine is desirable.

The following examples illustrate the invention.

Example 1.Preparation of N-hexachlor melamine Melamine, 126 grams, ismixed with water, 2000 grams to form a suspension and 400 grams ofacetic acid are added. The mixture is cooled to more acetic acid shouldbe added until this is the 8 case. After the mixture has stood 30minutes, with occasional agitation, the solid product is filtered oif,washed with water containing a little acetic acid, and dried at C. Theproduct is a light, loose white powder with a faint yellow tinge.Analysis shows it to be substantially pure N-hexachlor melamine havingthe formula CsNeClc Its molecular weight is 333, it has an activechlorine content of 128%, and its equivalent weight as anoxidizing agentis one-twelfth of its molecular weight, or 27.75. It is practicallyinsoluble in water, but soluble in benzene, carbon tetrachloride,ethylene dichloride, alcohol, kerosene and other organic liquids. Itdissolves in aqueous alkaline solutions with an orange color, and fromsuch solutions,,acids precipitate orange colored products containing asmaller proportion of active chlorine. Its use as a chlorinating agentto produce other N-chlor compounds is illustrated in Examples 1a and 1bin which lower N-chlor melamines are produced.

Example 1a.-Preparation of N-trichlor melamine Melamine, 126 grams,N-hexachlor melamine, 333 grams and water, 2,000 grams are mixedthoroughly. Then 20 grams of acetic acid are added, the mixture isheated at 50 C. for 30 minutes and allowed to cool. The solid product isseparated, washed with water containing a little acetic acid and driedat 80 C. In the process, one molecule of melamine and one molecule ofN-hexachlor melamine react to produce two molecules of N-trichlormelamine. Its formula is CaNeClaHa, its molecular weight is 229.5, itsactive chlorine content is 93 percent and its equivalent weight as anoxidizing agent is 38.25.

Example 1b.--Preparatz'0n of N-monochlor melamine In the same manner asin Example 1a, five molecules of melamine are caused to react with onemolecule of N-hexachlor melamine to produce six molecules of N-monochlormelamine. Formula, C3N5C1H5; molecular weight, 160.5; active chlorinecontent, 44.2 percent; equivalent weight as oxidizing agent, 80.25.

Example 2.-Preparati0n of N-chlor phthalimlde Phthalimide, 147 grams, ismixed with water, 2,000 grams and acetic acid, grams. The mixture iscooled to about 20 C. and while stirring, an aqueous solution containing80 grams of so- 5 dium hypochlorite is added. The pH is adjusted to lessthan 7 if necessary by adding more acetic acid. After the mixture hasstood 30 minutes, the solid product is removed, washed with watercontaining a little acetic acid and dried at 80 C. The product is a finewhite powder. It may be crystallized by dissolving in hot 50 percentacetic acid from which it separates on cooling in the form of smallmicaceous flakes. Formula molecular weight, 181.5; active chlorine, 39.1percent; equivalent weight as oxidizing agent, 90.75.

Example 3.Preparation of N-dichlor butylamine Normal butylamine, 73grams, is mixed with water, 750 grams and acetic acid 150 grams. To thesolution of butylamine acetate containing an excess of acetic acid whichis thus formed there is added, with cooling and stirring, an aqueoussolution containing 150 grams of sodium hypochlorite in 5 percentsolution. After one hour the colorless oily layer of N-dichlorbutylamine is separated, washed and dried. Formula, C4H9NCl2; molecularweight, 142; active chlorine content, 100 percent; equivalent weight asan oxidizing agent, 35.5.

Example 4.-Prepa atin of N-hexachlor triethylene tetramine The procedureof Example 1 is followed, using triethylene tetramine, 146 grams, water2,000 grams, acetic acid 450 grams and sodium hypochlorite 450 grams.The product is crystalline and has an active chlorine contentcorresponding to the formula Cl2N.C2H4.NCl.C2H4NCLC2H4NC12 Example5.Preparati0n of N-nonachlor melam The procedure of Example 1 isfollowed, using melam in pulverized form 235 grams, water 4000 grams,acetic acid 600 grams and sodium hypochlorite 675 grams. The product isa buff-colored powder with an active chlorine content corresponding tothe formula CsNnCls in which all nine atoms of N-hydrogen in melam, adeamination derivative of melamine, have been replaced by positivechlorine.

Example 6.--Preparation of N-chlorinated urea resin The procedure ofExample 1 is followed, using pulverized or precipitated urea resin '72grams, water 1,500 grams, acetic acid 150 grams and sodium hypochlorite155 grams. The product is a white powder containing approximately 100percent active chlorine.

Example 7.-Preparation of N-chlorinated casein Casein, powdered orfreshly precipitated, -90 grams, is mixed with water,-1500 grams, andacetic acid, '75 grams, is added. The mixture is cooled and stirredwhile adding a solution containing '75 grams of sodium hypochlorite in 5percent concentration. After the reaction mixture has stood for 30minutes, the solid product is filtered off and dried at a lowtemperature. N-chlorinated casein is a pale yellowish white solid havingan active chlorine content of about 57 percent.

Example 8.--Preparation of N-iodo succznimide Succinimide in finepowder, 99 grams, is mixed with water, 1000 grams and propionic acid 100grams. The mixture is cooled and while stirring, a solution of 254 gramsof iodine and 80 grams of sodium hydroxide in 6000 grams of water isadded. After one hour the solid product is separated, washed and driedat a low temperature. Its formula is C2H4(CO)2NI; molecular weight, 225:active iodine content 112.9%; equivalent weight 112.5.

Example 9.-Preparation of N-hexachlor melamine Sodium acetate, 860grams, is dissolved in liters of water. Chlorine is passed into theliquid unt l 440 grams have been absorbed. Then a suspension of 126grams of melamine in one liter of water is added. The solid product isremoved, washed and dried as in Example 1.

Example 10.Preparation of N-hexachlor melamine Melamine, 126 grams, issuspended in 10 liters of water in which has been dissolved 860 gramstinuously while chlorine gas, 440 grams, is passed in. The mixture isallowed to stand one hour, the solid product is filtered ofl, washedwith very dilute acetic acid and dried at C.

Example 11.-Preparatz'on of N-hexabrom melamine The procedure of Example1 is followed, using melamine, 126 grams, water, 2000 grams, acetic acid400 grams and sodium hypobromite 750 grams in 5 percent concentration.The product is a yellow powder containing percent active bromine.

Example 12.Preparation of N-hexaz'odo melamine The procedure 0'! Example1 is followed, using melamine, 126 grams, water, 2000 grams, acetic acid400 grams and sodium hypoiodite 1050 grams in 5 percent concentration.The product is a yellow powder containing 173 percent of active iodine.

I claim:

1. The process of preparing an organic N- halogen compound whichconsists in reacting an organic N-hydrogen compound, which is decomposedby a hypohalite salt acting alone, with a hypohalogen acid in an aqueoussolution having a pH below '7.

2. The process for the production of an organic N-halogen compound whichconsists in adding an aqueous sodium hypohalite solution to an organicN-hydrogen compound, which is decomposed by a hypohalite salt actingalone, in an aqueous solution of an excess of a weak acid.

3. The process of replacing by active halogen a definite proportion ofthe replaceable hydrogen attached to nitrogen in an organic compoundwhich is decomposed by a hypohalite salt actin alone which comprisesadding a regulated proportion of a hypohalite in water solution to anaqueous mixture containing the said organic compound together withsufficient acid stable toward positive halogen compounds to liberate allthe hypohalogen acid from its salt and to ensure a slight acid reactionat the end.

4. The process of preparing an organic N- halogen compound whichconsists in adding a halogen to an aqueous solution of a sodium salt ofa weak organic acid in presence of an organic N-hydrogen compound whichis decomposed by a. hypohalite salt acting alone.

5. The process for the production of an organic N-halogen compound whichconsists in treating an organic N-hydrogen compound, which is decomposedby a hypohalite salt acting alone, with a halogenating solution obtainedby adding a halogen to an aqueous solution of the sodium salt of anorganic acid.

6. The process of preparing N-nonachlor melam which consists in addingan aqueous solution of sodium hypochlorite to a suspension of melam inan excess or aqueous acetic acid and separating the solid product.

'7. The process of preparing an N-halogen derivative of aurea-formaldehyde condensation product which consists in adding anaqueous solution of sodium hypochlorite to a suspension of aurea-formaldehyde condensation product in an excess of aqueous aceticacid and separating the solid product.

11 12 8. The process or preparing N-hexachlor tri- Number Name Dateethylene tetramine which comprises adding a 2,184,888 Muskat 5, 1939solution 01 sodium hypochiorite to a solution of 2,299,089 Chenicek Oct.20, 1942 triethylene tetramine in an excess or aqueous acetic acid andseparating the solid product. OTHER mom 9. N-hexachlor triethyienetetramine. Chattflway. h ur- (87) 1905. PP-

WILLIAM c. ARSEM. 145-171.

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